Demographics is the study of statistical data relating to the population and particular groups within it. Demographic data of current population surveys includes density, spatial distribution, age, race, gender, income level, educational attainment, location, and homeownership.
One of the major sources in the United States is the national census. The Constitution mandates a survey be conducted every 10 years; the first federal census occurred in 1790. Census information expanded in the 19th century to include an economic census of manufactures and agriculture, eventually including wholesale, retail, and service establishments. A third type of census is a census of governments.
Statistical data is valuable on many levels. The Constitution mandated a count of the population in order to determine the number of legislators for each state in the House of Representatives, but the government also uses this information to develop policies and determine how to distribute federal monies to the states. U.S. census data is often used to forecast economic patterns and population growth to better manage expenditures. Socioeconomic data is also important to businesses, who use the information to learn more about their current and potential customers as part of their market research.